Lap



Aug. 19, 1930. R. GRoETcHEN LAP Original Filed April 18. 1927 Patented Aug. 19, 1930 PATENT orner;`

RICHARD erRoEfroHEN,4 or CHICAGO, iLLINoIs LAP Applicationl led April 18, 1927, Serial No. 184,566. Renewed November 14, 1929.

-This invention relates to a smoothing, lapping or polishing process and .to an apparatus for carrying out lsuch process. YIt has for one object to provide a lap, the major portion of which is permanent and in which the part subjected to abrasion and wear is removable. Another object is to provide a lap which. will automatically accommodate itself in lapping to holes of a relatively wide variation in size. Another Objectis to provide a process whereby a constantly moving and shifting layer of abrasive is vbrought up to carry out the lapping operation. Other objects will appear from timeto time in the course of the specification' and claims.

The invention is illustrated more or less diagrammatically in the accompanying drawings, whereinf o Figure 1 is a vertical cross-section of a piece during the lapping operation showing the lap and associated Aparts in elevation.

l Figure 2 is a perspective view of the permanent portion of the lapping device with the wearing part removed. I

`rFigure 3 is a perspective of the wearing part of the lap.

Figure 4 is a transverse cross-section taken on line 4 4: of Figure 1 and on an enlarged scale. f

Figure 5 is a view similar to Figure 4 in which the wearing part has been reversed in relation to the permanent part of the lap.

Figure 6 is a view similar to Figure 3, showing a modified formk of the wearing member.

Like parts are indicated by like characters y throughout the specification and drawings. A is a piece in which a perforation A1 has beenformed.

VB is any suitable rotating device in which the lap C is removably positioned.

LThe lap consists of a main shank portion C which' may have a reduced upper end C1 and which normally has formed about it anv outwardlyextending flange or ring C2., It

is provided in its outer or lower end with a slot G3, and preferably at the inner end of the slot it has an enlargement C4. It is also provided with a. plurality of circumferential slots C5 evenly spaced therealong.

Dy is a wearing member or part -formed in a generally cylindrical shape, provided with an inwardly bent flange or edge D1, which is circular with the axis of the member D. The member D is preferably so proportioned that when it is positioned upon the outer or lower end kof the lap C wit-lithc'tongue or flange D1 lying within the slot C3, its free edge will not meet the point X at which the flange D1 is. inwardly turned and there is thus left' a nar' row slot or groove'like portion X1. The member D is provided with `a plurality oi' apertures- D5 arranged in rows and positioned to overlie the circumferential grooves C5 ofthe member C. The location of said grooves and apertures inrelation to the members C and D is such that the member D is reversible and that it is impossible to put it on the member C and thrust it against the flange@2 without causing the apertures D5 to overlie the grooves C5. 4lhen the tool is in use, an abrasive or preferably a lubricant is applied to it, being inserted into the slot and this works down into the space X1 and forms a vertical strip of abrasive material extending 'throughout the length of the member D.. It also passesabout the grooves C5 andthrough the :apertures D, thus insuring a const-ant and uniform Ydistribution of the abrasive or lubricant throughout the surface of the member D. In the modiiied vform shown in Figure 6, a Wearing element is used inl which theabrasive material yforms a partof the wearing element and thus in effect, the wearing element is` impregnated with abrasive and forms in itself an abrasive element. This element maybe used with or without additional abrasive.

Referring to Figure V6 l illustrate the memi `ber D as imperforate, sinceunder certain preventing relative rotation of the sleeve and mandrel, said sleeve embracing the mandrel cireumferentially with the opposite ends of the split sleeve terminating in spaced relation, one of said ends being free to permit relative movement thereof with reference to the mandrel.

Signed at Chicago, county of Cook, and State of Illinois, this 15th day of April, 1927.

RICHARD GROETCHEN. 

